With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Dr. Yilin Hu from the University of California, Irvine, to investigate carbon dioxide activation by the iron protein of nitrogenase, the enzyme responsible for nitrogen fixation in microorganisms. Conversion of the greenhouse gas carbon dioxide into valuable chemicals represents an effective strategy to simultaneously combat the problems of increased carbon dioxide emission into the atmosphere and the decreased supply of fossil fuels. However, activation or splitting of carbon dioxide normally requires high temperature and pressure conditions, which puts a tremendous burden on our energy supply and environmental wellness. This pursuit focuses on just how the reaction takes place by a simple iron-sulfur enzyme, which will provide a crucial framework for future adaptations of this novel type of reaction for recycling the greenhouse gas carbon dioxide into useful products. As such, it has broad scientific impacts on our society by addressing two of the most important challenges we face nowadays: fossil fuel depletion and climate change. In addition, incorporation of this research into training of current students and outreach to prospective students raises public interest and awareness of the importance of this line of research and, therefore, has broader impacts on the education of future generations.
This project investigates the mechanism of in vitro carbon dioxide activation by the iron protein of nitrogenase and the engineering of an Azotobacter vinelandii strain with improved efficiency of in vivo carbon dioxide reduction upon expression of the iron protein. Guided by theoretical calculations, the proposed research employs a combination of genetic, biochemical, spectroscopic and structural approaches to tackle the unique reaction of carbon dioxide reduction by the all-ferrous iron protein and address several fundamental questions related to the mechanism of this reaction. Further, a combination of screening and expression strategies are used to identify iron proteins or homologs with higher efficiencies of carbon dioxide reduction and improve the specificity of electron transfer to the iron protein during the process of carbon dioxide reduction. The outcome of these studies provides important insights into how iron-sulfur based catalysts work to effect carbon dioxide activation and reduction under ambient conditions and what principles can be derived from studies of A. vinelandii for future development of cost-efficient, whole-cell-based strategies for carbon dioxide conversion.
